A fuel cell may convert the chemical energy of a fuel directly into electricity without any intermediate thermal or mechanical processes. Energy may be released when a fuel reacts chemically with oxygen in the air. A fuel cell may convert hydrogen and oxygen into water. The conversion reaction occurs electrochemically and the energy may be released as a combination of electrical energy and heat. The electrical energy can do useful work directly, while the heat may be dispersed.
Fuel cell vehicles may operate on hydrogen stored onboard the vehicles, and may produce little or no conventional undesirable by-products. Neither conventional pollutants nor green house gases may be emitted. The byproducts may include water and heat. Systems that rely on a reformer on board to convert a liquid fuel to hydrogen produce small amounts of emissions, depending on the choice of fuel. Fuel cells may not require recharging, as an empty fuel canister could be replaced with a new, full fuel canister.
Metal/air batteries may be compact and relatively inexpensive. Metal/air cells include a cathode that uses oxygen as an oxidant and a solid fuel anode. The metal/air cells differ from fuel cells in that the anode may be consumed during operation. Metal/air batteries may be anode-limited cells having a high energy density. Metal/air batteries have been used in hearing aids and in marine applications, for example.
It may be desirable to have a fuel cell and/or a metal/air battery having differing characteristics or properties than those currently available.